The evolution of the Changjiang Delta is obviously affected by current rapidly rising sea level and drastically declining river discharge,and it is also vital for the sustainable development of Shanghai and the Changj...The evolution of the Changjiang Delta is obviously affected by current rapidly rising sea level and drastically declining river discharge,and it is also vital for the sustainable development of Shanghai and the Changjiang River Economic Belt,which represent China’s economic development leader and major national strategic area,respectively.In this paper,the growth pattern of Jiuduansha Island,the largest uninhabited alluvial island in the Changjiang Estuary,is studied in terms of the change in elevation,position and area over the past 50 years through using satellite-derived instantaneous shoreline positions and high/low tide exposure areas based on 497 satellite images from 1974 to 2020;and the influencing factors and future development patterns are further discussed by comparison with other alluvial islands or sandbars in the estuary.The results show that Jiuduansha Island has maintained a rapid or even accelerated area growth rate,although the sediment discharge of the Changjiang River has sharply decreased in recent decades.This sustained growth is mainly attributed to the existence of the estuarine turbidity maximum zone,coarsening fluvial sediment,onshore sediment replenishment by tide,cone-like geomorphology of Jiuduansha Island,and siltation promotion effect of vegetation.The growth rate of the low tide exposure area of Jiuduansha Island increased from 1.9 km^(2)a^(−1) in 1974–1990 to 3.0 km^(2)a^(−1) in 1990–2020,and the growth rate of the high tide exposure area reached as high as 3.7 km^(2)a^(−1) in 1994–2020.The implementation of the Deep-Water Channel Project has significantly affected the evolution of Jiuduansha Island,including shifting the heads of Shangsha and Zhongxiasha from severe retreat to rapid accretion,and promoting tidal flat progradation seaward of the Jiangyanansha and Zhongxiasha,but restricting the growth of the low tide exposure area of Jiuduansha Island.展开更多
对大凌河河口地区ZK3钻孔(孔深36.7m)岩心开展粒度分析、AMS14C年代测定、有孔虫鉴定分析等综合研究,同时结合该地区5口工程钻孔的岩心以及部分测年资料,初步建立了大凌河河口地区晚更新世晚期以来典型的地层序列格架和时空对比框架,揭...对大凌河河口地区ZK3钻孔(孔深36.7m)岩心开展粒度分析、AMS14C年代测定、有孔虫鉴定分析等综合研究,同时结合该地区5口工程钻孔的岩心以及部分测年资料,初步建立了大凌河河口地区晚更新世晚期以来典型的地层序列格架和时空对比框架,揭示该地区晚更新世晚期以来河道-湖沼-滨海/河口湾-浅海-三角洲的沉积演化过程。研究结果表明:大凌河河口地区在8 500cal a BP前后开始接受海相沉积,并约在4 000cal a BP之后进入三角洲沉积阶段;晚更新世晚期以来的海平面变化是大凌河河口沉积演化和沉积环境演变的主要控制因素;大凌河对现代辽河三角洲的形成和演化过程可能有较重要的影响。展开更多
基金Thanks are due to Profs. Zhen Du and Li Xiaowen of the Chinese Academy of Sciences （CAS） for their instructions and encouragement. Special thanks to Profs. Yang Qinye, Wu Shaohong, Gong Peng, Liu Qinhuo, and Susan Kaspari for their great help with the research. The work is supported by the Special Funds for Major State Basic Research Project （Grant No. 2002CB412408）, by the National Natural Science Foundation of China （Grant Nos. 40371093, 40201005, 40471097）, by 0pening Fund projects of State Key Laboratory of Remote Sensing Science in the Institute of Remote Sensing Applications （Grant No. SK040006）, by 0pening Fund projects of State Key Laboratory of Estuarine and Coastal Research of East China Normal University （Grant No. 0310）.
文摘基于风景生态学 andGee 信息 Tupu 的图形、量的方法论，这篇论文学习风景黄河三角洲(YRD ) 的空间时间的进化特征，它被黄河(年) 尾部隧道的周期的物理秋千在 1855-2000 期间建立。根据关于 YRDand 年尾部隧道的空间时间的进化的研究，我们断定 Qingshuigou 隧道到达了它的限制，一条新流动隧道迟早多年应该被建立。它建议年隧道的移动应该接受它在以前的隧道之中通过消沉流动的自然规则并且能被人造的努力执行。论文在河口在 YR 流动为淤泥的高内容的处理外面讨论这些问题和交替的方法。
基金supported by the National Natural Science Foundation of China(Grant No.41776052)Shandong Provincial Natural Science Foundation,China(Grant No.ZR2019MD037).
文摘The evolution of the Changjiang Delta is obviously affected by current rapidly rising sea level and drastically declining river discharge,and it is also vital for the sustainable development of Shanghai and the Changjiang River Economic Belt,which represent China’s economic development leader and major national strategic area,respectively.In this paper,the growth pattern of Jiuduansha Island,the largest uninhabited alluvial island in the Changjiang Estuary,is studied in terms of the change in elevation,position and area over the past 50 years through using satellite-derived instantaneous shoreline positions and high/low tide exposure areas based on 497 satellite images from 1974 to 2020;and the influencing factors and future development patterns are further discussed by comparison with other alluvial islands or sandbars in the estuary.The results show that Jiuduansha Island has maintained a rapid or even accelerated area growth rate,although the sediment discharge of the Changjiang River has sharply decreased in recent decades.This sustained growth is mainly attributed to the existence of the estuarine turbidity maximum zone,coarsening fluvial sediment,onshore sediment replenishment by tide,cone-like geomorphology of Jiuduansha Island,and siltation promotion effect of vegetation.The growth rate of the low tide exposure area of Jiuduansha Island increased from 1.9 km^(2)a^(−1) in 1974–1990 to 3.0 km^(2)a^(−1) in 1990–2020,and the growth rate of the high tide exposure area reached as high as 3.7 km^(2)a^(−1) in 1994–2020.The implementation of the Deep-Water Channel Project has significantly affected the evolution of Jiuduansha Island,including shifting the heads of Shangsha and Zhongxiasha from severe retreat to rapid accretion,and promoting tidal flat progradation seaward of the Jiangyanansha and Zhongxiasha,but restricting the growth of the low tide exposure area of Jiuduansha Island.
文摘对大凌河河口地区ZK3钻孔(孔深36.7m)岩心开展粒度分析、AMS14C年代测定、有孔虫鉴定分析等综合研究,同时结合该地区5口工程钻孔的岩心以及部分测年资料,初步建立了大凌河河口地区晚更新世晚期以来典型的地层序列格架和时空对比框架,揭示该地区晚更新世晚期以来河道-湖沼-滨海/河口湾-浅海-三角洲的沉积演化过程。研究结果表明:大凌河河口地区在8 500cal a BP前后开始接受海相沉积,并约在4 000cal a BP之后进入三角洲沉积阶段;晚更新世晚期以来的海平面变化是大凌河河口沉积演化和沉积环境演变的主要控制因素;大凌河对现代辽河三角洲的形成和演化过程可能有较重要的影响。
